Cowl doors are utilized in aircraft jet engine housings to provide for convenient access to the interior engine components for inspection, service and repair. Typically, two such cowl doors are employed at each side of the engine housing and are hingedly connected at their top ends to the housing so that they can be swung open and closed by raising and lowering the same. To open or raise the cowl doors, which may be quite large and heavy on the larger jet engines, single ended hydraulic actuators are employed. Such actuators are pivotally connected by suitable bearings between the cowl doors and the engine housing so that upon powered extension thereof, the door will be moved from its closed or lowered position to its open or raised position. To close the door, the actuator is depowered so that the door will swing down either from its own weight or with manual assistance. When the door is closed, suitable locks are provided to maintain the door in its closed position while the actuator remains in its depowered or passive state.
It has been found in cowl door assemblies of the aforementioned type that fretting of the actuator piston rods and the connecting bearings can occur due to flight vibrations when the cowl doors are closed and the actuators depowered. Such fretting may necessitate premature replacement of the actuator and/or bearings which in both time consuming and costly, and in any event, undesirable.